Biology Ch9 Genetics

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Heredity

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the transmission of characteristics from parents to offspring

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trait

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a genetically determined variant of a characteristic

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pollination

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pollen grains produced in the pollen grains from the male reproductive parts of a flower, the anthers,are transferred to the female reproductive part of a flower, the stigma

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self pollination

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pollen is transferred from the anthers of a flower to the stigma of either that flower or another flower on the same plant

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Cross-pollination

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transfer of pollen between flowers of two plants

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true-breeding

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(pure-breeding) plants that always produce offspring with the same trait when self-pollinating

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P generation

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true-breeding parents for contrasting traits of a single characteristic

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F generation

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the first filial generation produced by cross-pollination of two P generation parents

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F generation

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the generation produced by self-pollination of the f generation

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Dominant factor

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masks the factor for the other trait in a pair, when cross-pollinating the P generation

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Recessive factor

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a trait that will not appear in the F generation but will reappear in the F generation in a ration of 3:1

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Law of Segregation

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a pair of factors or traits is separated during the formation of gametes

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Law of Independent Assortment

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Factors for individual characteristics separate independently of one another during the formation of gametes. Note: this observed only for genes located on separate chromosomes or those located far apart on the same chromosome

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Molecular Genetics

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study of the structure and function of chromosomes and genes

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Allele

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each of two or more alternative forms of a gene is called a factor, or an .....

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Dominant Allele

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Capital Letter

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Recessive Allele

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lowercase letter

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Genotype

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an organism's genetic makeup; consists of the alleles that an organism inherits from its parents

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Phenotype

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an organism's appearance, does not always indicate the genotype because of recessive alleles and environmental factors

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homozygous

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both pairs of alleles are alike

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heterozygous

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the two alleles in a pair are different

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Probability

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the likelihood that a specific event will occur; can be expressed as a decimal, a percentage, or a fraction

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Probability

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number of times an event is expected to happen
_________________________
number of times an event could happen

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Monohybrid(s)

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a cross in which only one characteristic is tracked; the offspring of such a cross

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Punnett Square

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a diagram used to aid in predicting the probable distribution of inherited traits in offspring

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genotypic ratio

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the ratio of genotypes that appear in offspring

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phenotypic ratio

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the ratio of the offspring's phenotypes

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testcross

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used to determine the genotype of any individual whose phenotype expresses the dominant trait; the cross of an unknown genotype with a homozygous recessive genotype

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complete dominance

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heterozygous organisms and homozygous organisms are indistinguishable in phenotype

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incomplete dominance

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when offspring have a phenotype in between that of the parents

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Codominance

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both alleles for a gene are expressed in a heterozygous offspring; neither allele is dominant or recessive, nor do the alleles blend in the phenotype

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dihybrid cross

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a cross in which two characteristics are tracked